3 The technology
3.1 A CPAP device consists of a unit that generates airflow, which is directed to the airway via a mask. Positive pressure is generated by the airflow, which prevents upper airway collapse. For CPAP treatment to be effective the person must always wear their device when they go to sleep.
3.2 Reasons for not adhering to CPAP treatment include poor mask fit, pressure intolerance and, more commonly, upper airway symptoms such as nasal dryness, nasal bleeding and throat irritation. Humidification devices are now commonly used in conjunction with CPAP devices in order to reduce these side effects. Masks should be replaced at least annually, and long-term follow-up of patients is critical to ensure adherence.
3.3 There are two types of CPAP devices. Fixed CPAP devices deliver air at constant pressure throughout the night, and the person will continue to receive this pressure until a further titration study is performed to determine whether the set pressure is still appropriate. Auto-titrating CPAP devices continually adjust the pressure delivered throughout the night, with the aim of improving comfort and thus adherence.
3.4 CPAP devices available in the UK are the SleepStyle 230 and 600 series (Fisher & Paykel Healthcare), the S8 series (ResMed (UK)), the RPM BiLevel 9055, RPM 9054, AutoAdjust and Horizon range (Sunrise Medical – DeVilbiss), the GoodKnight 420 series (Tyco Healthcare), the Breas range (Vital Signs) and the REMstar series (Respironics UK).
3.5 The price of CPAP devices ranges from £250 to £550 (pricing information obtained from manufacturers' submissions or NCCHTA briefing notes). Costs may vary in different settings because of negotiated procurement discounts. The lifespan of a CPAP device has been reported to be approximately 7 years. The lifespan of a mask is 6–12 months.